There are different types of propane tank valves that are commonly used in the market today. POL valves are traditional propane tank valves that can be tightened in place using a wrench. These valves come with a plug, which is used to prevent gas leaks when the actual POL valve isn’t connected to an appliance. The POL valve also features bleeder valves along with pressure relief devices, which are built into the device to monitor propane gas supplies and contents.
The acme valve is another popular type of propane tank valve. They use acme threads and much larger grill fittings for easier connection. Acme valves also feature built-in safety controls for added user protection. OPD or overfill prevention devices, on the other hand, are designed to prevent gas leaks and overfilling when transferring propane from cylinders. These valves feature an internal float, which works to prevent overfilling. Modern LPG tanks utilize OPD valves, although adapters for this kind of fitting are also available so older tanks can be used with modern appliances.